A program can determine if ISPF services are currently available to it through use of ISPQRY. To test the availability of ISPF, the function issues:

   CALL ISPQRY;

There are no parameters associated with the call to ISPQRY. No messages are written to the terminal. The response from ISPQRY is one of these return codes:

 0

The services are available to the caller.

20

The services are not available to the caller.